Cutoff structure for circuit breaker

ABSTRACT

The cutoff structure for a circuit breaker comprising, for each pole, a contact bridge (17) lodged in a push button (20). The push button is guided in a fixed cage (21) mounted in the box of the circuit breaker, the cage being fitted with passage windows (24) for the contact bridge and with an upper stop (26) for the bridge, so as to constitute a telescopic sub-assembly.

This invention relates to a cutoff structure with contact bridge forcircuit breaker comprising, in a box and for each pole, a mobile contactbridge associated with fixed contacts and a contact pressure spring, thebridge being pushed against the spring by a push button which is securedto a mechanism for opening and closing the contacts.

Such structures are well known and, in combination with arcextinguishing assemblies, have as function to open the contacts of therespective poles in response to a command that is voluntary orsubsequent to an electrical fault communicated to the opening-closingmechanism. Experience has shown that it is desirable to confer, uponsuch a contact-holder structure, additional functions facilitating theassembly and/or functioning of the circuit breaker.

In particular, the object of the invention is to transfer, to thestructure with contact bridge, functions such as push button guidanceand/or arc confinement functions, usually devolving upon the circuitbreaker box.

According to the invention, the push button of the contact bridge isguided in a fixed cage mounted in the circuit breaker box. The pushbutton guidance function is therefore transferred to the cutoffstructure. When the fixed cage has a stop for the contact bridge in thedirection corresponding to the springing back of the spring, the cutoffstructure can be constructed as a telescopic sub-assembly fitting easilyinto the circuit breaker box.

The push button preferably comprises at least one port dimensioned toallow introduction of the contact bridge and an angular clearance of thebridge in relation to the push button, the clearance being thus madepossible though the push button is guided for translation in the fixedcage.

In a preferred embodiment, the fixed cage comprises insulating lateralwings and a corresponding extension of its base wall for constitutingcutoff prechambers that can be embraced by the ends of fins of arcextinguishing structures.

The invention will now be explained by a description of a non-limitingexample, in reference to the following figures:

FIG. 1 represents an exploded perspective of a circuit breaker mountingbase equipped with cutoff structures according to the invention;

FIG. 2 is an elevation of a first embodiment of the cutoff structure;

FIG. 3 is an elevation of a second embodiment of the cutoff structure,with partial representation of neighbouring elements of the circuitbreaker box;

FIG. 4 is a side view according to arrow F of FIG. 3;

FIG. 5 is a top view, with partial illustration of neighbouringelements.

The circuit breaker illustrated in FIG. 1 comprises a box in insulatingmaterial 10 of which are represented only the mounting base part and, inthis box, several polar current paths each equipped with a cutoffstructure S with separable contacts. In this way, each polar pathcomprises two fixed contacts 11, 12 disposed on fixed contact parts 13,14 connected to terminals that are not indicated. It further comprisestwo mobile contacts 15, 16 respectively associated with the fixedcontacts 11, 12 and disposed on an electrically conductive and mobilebridge 17 to constitute a double-cutoff polar switch. Of the elements ofthe box cooperating with the cutoff structure, a base wall 18 andpartitions 19 between the poles can be noted.

The mobile contact bridge 17 is acted upon by a mechanism (notrepresented) for opening and closing the contacts, by means of a pushbutton 20 guided according to the invention in a fixed cage 21. The cage21 is in an insulating material and comprises a base wall 22, side walls23 perpendicular to the partitions 19 between the poles, and fitted withwindows 24 and blank side walls 25 parallel to the partitions 19. Thebase wall 22 of the cage is positioned on the mounting base 18 of thebox 10.

FIG. 2 illustrates further details of a first embodiment of the cutoffstructure S. It should be noted that the windows 24 of the side walls 23of the fixed cage are dimensioned to enable displacement of the contactbridge, notably under the effect of the opening-closing mechanism in thecase of electrodynamic repulsion. In addition, the windows 24 determinean upper stop 26 for the contact bridge 17. A contact-pressure helicalspring 28 is lodged between the base wall 22 of the cage and the contactbridge 17 in a central recess 29 of the cage 21 which also serves tolodge and to guide the push button 20 for translation. The latter isthus guided against the inner sides of the side walls 23, 25 of the cageby respective walls 30, 31. The walls 30 of the push button are indentedby ports 32 dimensioned to enable, on the one hand, introduction of thebridge in the push button, and, on the other hand, angular clearance ofthe bridge in relation to the push button. A central orifice 33 isprovided in the push button to allow the spring 28 to pass. The basewall 22 of the fixed cage has a recessed part 34 serving for the passageof a flat and bent arc deflection part connecting the respective cutoffchambers 36, 37 to one another.

In the embodiment in FIGS. 3 to 5, the fixed cage 21 of the cutoffstructure S comprises insulating wings 38 parallel to the partitions 19between the poles and extending longitudinally over a distance slightlygreater than the length of the bridge 17 and sufficiently high to createa volume containing the interruption arcs. Finned assemblies 39, whosefunction it is to divide the arcs into fractions and extinguish them,comprise a certain number of fins 40, generally U-shaped and opentowards the contacts side. The U-shaped open area embraces, by means ofits wings 41, the insulating wings 38 of the fixed cage.

The base wall 22 of the fixed cage advantageously protrudes to lodgeitself in a central cavity 42 corresponding to an outward protrusion ofthe base 18 of the box 10, in order to reduce the overall height of thecircuit breaker. Pins 43 are provided on the bridge 17 for cooperatingwith corresponding forms in the walls 30 of the push button 20, in orderto maintain the bridge centered in relation to the push button.

The wings 38 of the cutoff structure can be seen to define, with acorresponding shell 44 which extends the base wall 22 of the cage,cutoff prechambers 45, 46 lodged in the chambers 36, 37. The fixed cage21 is advantageously in a different material to that of the mountingbase of the box since the cage withstands the main cutoff constraints.The structure described with regard to a circuit breaker applies, ofcourse, to different protective switch devices, notably to directionalrelays.

I claim:
 1. A cutoff structure for circuit breaker comprising a box ininsulating material having at least one partition wall separating atleast two polar current paths, each current path comprising:a mobilecontact bridge associated with fixed contacts and urged against saidfixed contacts by a contact pressure spring, said bridge being pushedagainst said spring by a push button which is secured to a mechanism foropening and closing said contacts, a cage in insulating materialremovably fixed in said box and comprising means for guiding said pushbutton, passage windows for said contact bridge, enabling displacementof said contact bridge under the effect of said mechanism and in thecase of electrodynamic repulsion, and insulating lateral wingsdelimiting an arc confinement volume enclosing said contact bridge. 2.The structure as claimed in claim 1, wherein said fixed cage has a stopfor said contact bridge in the direction corresponding to the springingback of said spring.
 3. The structure as claimed in claim 1, whereinsaid push button bears said contact bridge and comprises at least oneport dimensioned to allow introduction of said contact bridge into saidpush button and an angular clearance of said bridge in relation to saidpush button.
 4. The structure a claimed in claim 1, wherein saidinsulating wings are embraced by open areas of finned arc extinguishingassemblies.
 5. The structure as claimed in claim 1, wherein said fixedcage comprises a base wall positioned on the mounting base of said box.6. The structure as claimed in claim 5, wherein there is provided,between said base wall of said cage and said mounting base of the box, aflat deflector connecting the cutoff chambers to one another.
 7. Thestructure as claimed in claim 1, wherein the material of said fixed cagediffers from that of the neighbouring areas of said box of said circuitbreaker.